1. Field of the Invention
The present invention generally relates to keyboards for electronic instruments and, more particularly, is concerned with a keyboard having raised keys forming an implied tetrahedral shape with the base of the keyboard for facilitating use.
2. Description of the Prior Art
The frequent use of computers and other keyboards can cause serious physical injury and pain to the wrists and other areas of the arms of the users. This is generally caused through repetitive motion on the keyboards by the user's fingers on the keys. These disorders are generally known as cumulative-trauma disorders or repetitive-motion injuries resulting from the repetitive motion of the hands on the keyboards. As more and more individuals are using computer keyboards on a continuous and repetitive basis, these types of disorders are becoming more and more prevalent amongst computer users. Such repetitive use can also cause physical damage to the wrist, and more particularly to the carpal tunnel, known as Carpal Tunnel Syndrome, which can cause serious weakening of the hands and reduction in dexterity.
The standard monoplane keyboard, that being a keyboard defining one plane and lying generally flat on a table, exacerbates the problems associated with repetitive-motion injuries. The monoplane keyboard forces the user to rotate his or her forearms from a relaxed position to an extreme position so that the fingertips of each hand are horizontal. As well, both wrists must be flexed away from the thumb side of the hand in order to line up the fingertips with the longitudinal rows of keyboard keys. It has been determined that repositioning of the keyboard to permit more "natural" or unflexed positioning of the forearms and hands should significantly reduce the stress on the wrist and elbows, thereby reducing the instances of repetitive-motion injuries resulting from the use of computer keyboards.
An example of a keyboard in which the demi-boards are positioned in an A-frame orientation is disclosed in U.S. Pat. No. 4,509,873 issued to Ryan. The Ryan patent discloses a computer keyboard incorporating a base member having a distal face for orienting away from the user and an adjacent face for orientation adjacent a user and a pair of demi-boards which may be split in an A-frame orientation. Adjustment from a flat horizontal position to an angled position is achieved through the raising of the central portion of the demi-boards from the flat base member. The base member is angled so that the distal side is higher than the adjacent side. As well, the intersecting point of the two demi-boards is perpendicular to the plane of the top face of the base member.
As well, U.S. Pat. No. 4,597,681 to Hodges discloses the use of an adjustable keyboard having a base member and a pair of demi-boards which may be raised at their joining edge into an A-frame configuration. As well, each demi-board may be pivoted within its respective plane about an axis perpendicular to that plane. Hodges provides a generally flat base member with a generally dish-shaped surface of the keys. The keys may be positioned in a non-planar manner on each demi-board.
Each of these A-frame type adjustable keyboards, while representing an improvement over the monoplane keyboard in terms of hand positioning, do not generally provide sufficient optimization of wrist and forearm positions when the fingers are placed in contact with the key faces. These keyboards still force the user to bend the wrists upwardly and/or outwardly to align the fingertips with the keys on each demi-board. It is not possible, if one is to maintain proper finger alignment to the keys, to orient the wrists in linear alignment with the forearm, as the planes of the demi-boards in an A-frame orientation are still parallel to the proximal-distal axis of the keyboard base. In other words, a user is still forced into a position where his wrists are bent backwards to some degree forming an angle with the forearm, in order to properly contact such a keyboard.
Consequently, there is a need for a keyboard with adjustable demi-boards which may be raised, with respect to a base member, in a position wherein the distal edge of the demi-boards is oriented inwardly as compared to the adjacent edges of the demi-boards so that the demi-boards parallel the forearms of the user and so that the fingertips of the user may contact the keys on the demi-boards while the wrist and forearms are in substantial linear alignment.